实验性
Base class for item components.
只读
返回组件是否有效。若组件的拥有者有效，并且组件需要的任何 额外验证也通过，则该组件被认为是有效的。
Returns whether the component is valid. A component is considered valid if its owner is valid, in addition to any addition to any additional validation required by the component.
组件的标识符。 Identifier of the component.
Base class for item components.